chatroom auto logoff?

[alivy]

hello
I'm a Chinese php user. I hope I can describe my problem well in English.

I'm building a chatroom by php (Apache 2, php4, and MySQL).
I use a table in MySQL to save the informations of the users who is online now. The table includes current users' name, last response time, and rank.
There is 1 user can speak at one time, and the webmasters always have the authority of speaking. The authority is determined by the rank. Webmaster's rank is 1, the user who log on first in all current users has rank 2, the others has rank 0. Only rank 1 and 2 has the authority of speaking.

I built a page which renews every 10 seconds to:
1. get current user's username by session ( i've started a session after he or she log in)
2. compare the username with the usernames in the online user table.
if has the same name, then get current time and update this username's last response time.
if hasn't the same name, then insert a new user and use current time as it's last response time.
3. compare every username's last response time with current time, if the margin is larger than 30 seconds, then delete the user in the online table.

To test it, I opened several IE windows in my notebook, logged in with different users. Then the users AUTO LOST THE SPEAKING AUTHORITY one by one until there is only one user (no matter it's webmaster or not)! Then I used two computers to test it, but the problem was still there.
Then, because there's a page only provides the log in function, I logged in two users at one time, but haven't enter the chatroom, but they are all online after a long time.
Then, I deleted the function which is delete the no-response user in the online table. But the problem was remain.

So I think it's session's problem.
Why it will inefficient after a while? And why when there is only one user, it's session will always available?

btw, session.cookie_lifetime=0 in my php.ini
and when the session started, i haven't given the time parameter to it.

THANKS!

[alivy]

no one understands me?🙁 🙁

[alivy]

this is my code

LOG IN PAGE:

<?
//if exist Session
if ($username)
{
$query="select * from $table where name='$username'";
$result=mysql_db_query($database, $query);
$getinfo=mysql_fetch_array($result);
$count=$getinfo["count"];
$tureuser=1;
}

//if no Session exists
elseif ($entername)
{
$query="select * from $table where name='$entername'";
$result=mysql_db_query($database, $query);
$getinfo=mysql_fetch_array($result);
$enterpw=md5($enterpw);
if ($enterpw!=$getinfo["pw"])
{
$tureuser=2;
}
else
{
$tureuser=1;
$username=$entername;
session_register("username");
$count=++$getinfo["count"];
$query="update $table set count='$count' where name='$username'";
mysql_db_query($database, $query);
}

}
//$table contains every user's information
//i have simplify the variables which were gained from forms and the database
?>

ONLINE TEST PAGE:
<meta http-equiv="Refresh" content="5; url=onlinehide.php">
<?
//get current time
$nowstamp=mktime();
//judge current user's rank
$masterquery="select master from $table where name='$username'";
$masterresult=mysql_db_query($database, $masterquery);
$rank=mysql_result($masterresult,0);
//get id, webmasters' id is 0
$query="select max(id) from $onlinetable";
$result=mysql_db_query($database, $query);
$currentid=mysql_result($result,id);
++$currentid;
if ($rank==1) $currentid=0;
//
$existquery="select from $onlinetable where name='$username'";
$existresult=mysql_db_query($database, $existquery);
$exist=mysql_num_rows($existresult);
//if current username exists, update last response time
if ($exist)
{
$query="update $onlinetable set time=$nowstamp where name='$username'";
mysql_db_query($database, $query);
}
//if not, insert
else
{
$query="insert into $onlinetable values ('$username',$nowstamp,$currentid,$rank)";
$result=mysql_db_query($database, $query);
}
//delete user in the online table
//interval>30 seconds
$deletequery="delete from $onlinetable where $nowstamp-time>30";
mysql_db_query($database, $deletequery);
//
$checkquery="select from $onlinetable where rank=2";
$checkresult=mysql_db_query($database, $checkquery);
$checknum=mysql_num_rows($checkresult);
//give speaking authority to the user who is the first in the online table
if (!$checknum)
{
$query="select min(id) from $onlinetable where rank=0";
$result=mysql_db_query($database, $query);
$grantid=mysql_result($result,id);
$grantquery="update $onlinetable set rank=2 where id=$grantid";
mysql_db_query($database, $grantquery);
}
//display current online state
$query="select * from $onlinetable order by id asc";
$result=mysql_db_query($database, $query);
$onlinenum=mysql_num_rows($result);
echo "now online",$onlinenum,"<br>";
for ($now=0;$now<$onlinenum;++$now)
{
$name=mysql_result($result,$now,name);
$rank=mysql_result($result,$now,rank);
if ($rank==1) $status="(webmaster)";
elseif ($rank==0) $status="(waiting)";
elseif ($rank==2) $status="(speaking)";
elseif ($rank==3) $status="(banned)";

echo $name,$status,"<br>";
}
?>

THANKS!